In commerce, there is often a need to transfer a large quantity of liquid from a first vessel to a second vessel. Conventionally, a hose runs from the first vessel to a rigid coupling termination, and another hose runs from the second vessel to a rigid coupling termination. The coupling of the first hose is connected to the coupling of the second hose, and then liquid is controlled (by valves, pumps and the like) to flow from the first vessel, through the connected hoses and into the second vessel. When dealing with a high rate and intermittent liquid flow, a lot of stress may be exerted on the connection between the couplings of the hoses. Therefore, the means for connecting the couplings must be designed to handle this large stress.
One example of this liquid transfer situation is the loading of gasoline between a storage tank and a tank on a tanker trailer. A hose runs from a gasoline tank to a rigid tank-side coupling having opposing latches. Another hose runs from the tanker trailer to a rigid trailer-side coupling having a surface to receive the latches. When the two couplings are connected the opposing latches of the tank-side coupling tightly clamp the receiving surface of the trailer-side coupling to effect a strong connection between the hoses. With this strong connection, a large and intermittent volumetric flow of gasoline will not compromise the connection between the hoses, and the transfer of gasoline between the tank and tanker trailer can be quickly accomplished.
Some conventional embodiments of this kind of tank and trailer couplings are disclosed in U.S. Pat. No. 5,407,175 to Roberts et al., which is herein incorporated by reference. More specifically, Roberts et al. disclose a removable fluid coupling (i.e., a tank-side coupling) which can latch an annular surface of a flow valve (i.e., a trailer-side coupling).
Roberts et al. recognize that the latches of the fluid coupling cause wear on the annular receiving surface of the flow valve. The flow valve embodiments of Roberts et al. are constructed so that the annular receiving surface is located on a detachably attachable annular flange which fits around the body of the flow valve and can be secured thereto at various angular orientations. When the latches begin to cause sufficient wear at portions of the annular flange, the annular flange is removed and repositioned to a different angular orientation so that different, unworn portions of the annular flange receive the latches. Because the annular flange can be repositioned to be worn down at several positions, the life of the annular flange part is extended.
Of course, manual labor is required to periodically monitor and reposition the annular flange. Also, the means for detachably attaching the annular ring to the body of the flow valve must be provided at some cost. For instance, tapped holes and/or set screws, and further, this means for detachably attaching may be subject to mechanical failure.
In another conventional design for a trailer-side coupling, an annular receiving surface is made integrally with the body of an aluminum trailer-side coupling. The portion of the trailer-side coupling with the receiving surface is then treated to harden and provide additional wear resistance on the annular receiving surface. After treatment, the surfaces of the treated portions become rough, so the coupling is then remachined to smooth certain surfaces, such as the poppet valve seat. By this treatment, the latches of the tank-side coupling will cause less wear, thereby considerably extending the life of the trailer-side coupling.
However, the treatment and remachining are expensive processes and increase the amount of material required to make the coupling. Also, the fact that the treated products must be remachined after treatment can cause logistical and scheduling problems.